What is it about this era that inspires vertical construction? By the end of this year an astonishing 82 skyscrapers will stand above 985 feet (the official cutoff for “supertall” status), up from 34 in 2007. Supertall construction provides a modern global aesthetic. Its architecture conveys myths of orderly, successful cosmopolitanism, even if the city streets below may not have the same social tidiness. Vertical imagery even pervades the culture of advertizing: Shanghai’s skyline adorns the Nook, a global collage of towers personifies the Financial Times, and Hong Kong’s blurry cityscape announces Fareed Zakaria’s bestselling Post-American World. Ethereal skylines give globalization its iconic urban appearance (the factories symbolizing the old economy look so gnomish by comparison!). They also bestow the promise of high-end knowledge sectors that may or may not transform local economies in a good way.

Recently I spent some time around two instructive pieces of vertical architecture that could presumably be competitors in a transoceanic race between the US and China for economic hegemony. One is the 1,614 foot Shanghai World Financial Center, finished in 2008. The other is Manhattan’s up-and-coming 1,776 foot World Trade Center One. Both sit (or will) at the center of massive high-tech downtown office clusters. The World Trade Center complex is rising at the speed of molasses, its slowness a purported example of the new American anemia in big ticket construction. This contrasts mightily with China’s damn-the-NIMBY reputation for finishing large undertakings on time and on budget. The Shanghai WFC nevertheless took a delay-laden 11 years to build, missing a good chance to temporarily become the world’s tallest building. Meanwhile an astonishing forest of cranes make Lower Manhattan’s Trade Center site (photographed above) look a lot like Shanghai, which is perennially under construction.

Both supertall towers have born their fair share of design criticism. The Shanghai WFC doesn’t offer the same sense of place as its current neighbor, the mechanical pagoda-style Jin Mao tower. World Trade Center One’s designs have been beset by an uneasy balance of aesthetics and security, and were dismissed as “posturing” by New York Times architecture critic Nicholai Ouroussoff. Each is part of larger mixed-use complexes in the tradition of garden city modernism, making organic development at the street level a worry. Shanghai planners, I’m told, are trying to somehow change course and make the Financial Center’s surrounding grand boulevards inviting for pedestrians. I’m guessing the Trade Center site will be somewhat better in this regard, but its street life will probably feel dull next to New York’s miraculous small scale districts.

But these megaprojects aren’t aiming for human scale. They are underpinned by a certain Darwinian ruthlessness that prevails in global business capitals. The logic goes like this: If cities don’t cast a pall over their streets with the latest, greatest, most imposing high-tech monoliths, then requisite global investments will go elsewhere. Cities need the hardware to accommodate top end knowledge sectors in an increasingly competitive economy that subjects localities to competition from everywhere else. Grounded in reality or not, that’s the narrative that justifies these massive projects. “Despite current reduced demand and lower rents,” argues the The New York Post’s Steve Cuozzo, “New York needs new office buildings. Most Manhattan buildings are more than 50 years old and inadequate for today’s financial companies; failure to replenish the stock threatens our long-term ability to compete globally.”

Shanghai, for its part, faces a massive shortage in knowledge workers despite all its impressive development efforts. For instance there are 198,000 financial sector employees in Shanghai compared with 770,000 in New York, reports the state-run Shanghai Daily. Shanghai has an ambitious plan to attract worldwide talent by providing state of the art infrastructure, along with plenty of luxurious entertainment germane to upper class tastes. The Shanghai WFC’s brochure bills it as a “vertical garden city” that combines all of these things in one (its developer is an ardent admirer of Le Corbusier’s utopian cityscapes). Its high-end facilities are intended to be a “global magnet” for “people, information, and cutting edge businesses from around the world.” So far it’s not as well magnetized as its developers would like, with reported 40 percent vacancies. As it stands, the Trade Center would be lucky to do that well.